Protective coating for storage-battery plates.



. creased thickness, while to a certain extent ACHILLE MEYGRET.

Patented November 29, 1904.

ATENT OFFICE.

OF PARIS, FRANCE.

PROTECTIVE COATING FOR STORAGE-BATTERY PLATES.

SPECIFICATION forming part of Letters Patent No. 776,480, dated November 29, 1904.

Original application filed June 29, 1903, Serial No. 163,637. Divided and this application filed July 27, 1903. Renewed April 6, 1904. Serial No. 201,915. (No specimens.)

To all whom it may concern:

Be it known that I, 'AGHILLE MEYenE'r, a citizen of the Republic of France, residing at Paris, in the Department of the Seine, France, have invented a certain new and useful Improvement in Protective Coatings or Coverings for Storage-Battery Plates, of which the following is a specification.

One objection found in the use of storagebattery plates which are constructed with a metal grid and a facing of active matter or material applied to the grid is the loosening and continual dropping off or detachment of the active matter or material. This loosening and dropping oif or detachment of the active matter or material arises mainly from the repeated charging and discharging of the bat tery, which causes the active matter or material to dilate and contract, and as the clasticity of the active material is very limited a loosening of the material follows, which loosening causes the active matter or material to drop off or detach itself from the grid, rendering the battery useless or in any event impairing its efficiency. A plate or grid of inovercoming the propensity of the loosening and continual dropping ofl of the active material from expansion and contraction, adds the objectionable feature of increased weight, which is excessive, and also an increase of size, both of which are undesirable and impracticable for certain uses and purposes.

The object of the present invention is to furnish a protective coating or covering to overlie the active matter or material on the grid and retain such material in place against the effects of expansion and contraction of the active matter or material, by which the same will become loosened and fall 011' or detach itself from the grid, and to attain thisresult without increasing the weight of the plate as a whole nor decreasing the active surface in connection with a thin plate and in no wise militating against the activity of the plate as a Whole.

The invention consists in the protective coating or covering applied to a storage-battery plate as hereinafter described and claimed.

The protective coating or covering is a solution of tetrabutyrat of cellulose, which solution when used by dipping the plate therein makes a protective coating or covering inclosing the active matter or material.

The plates or electrodes of a battery can be of any usual and Well-known form of construction, consisting of a metal grid and a filling of active matter or material applied to the grid. The plate after the filling of active matter or material has been applied thereto.

is to be dipped in the solution of tetrabutyrat of cellulose for the solution to adhere to and form a coating or covering over the active material. This protective coating or covering forms, in effect, a sheath or film, inclosing within it the active matter or material, holding the same to the surface of the grid against the effects of expansion and contraction of the active matter or material in charging and discharging the plate. The solution of tetrabutyrat of cellulose makes a sheath or film when applied to the plate that is elastic and at the same time impervious to the attacks of the electrolyte, thus furnishing what may be termed a binding that will prevent the active matter or material from becoming loosened and falling OH? or detaching itself from the plate. The sheath or envelop formed by the solution named being impervious to the attacks of the electrolyte, in order to have the electrolytic reactions of charging and discharging produced by the electrolyte on the active matter or material provision must be made that will allow of the electrolyte reaching the active material without coming in direct contact with the metal of the grid, and for this purpose the envelop or sheath forming the protective coating or covering for the active matter or material must be given or have a certain amount or degree of porosity. The required porosity for the envelop or sheath can be obtained either by passing the completed plate under a cylinder provided with fine needle-points that will perforate the outer envelop or sheath without destroying its continuity or by cutting a series of fine gashes in the envelop or sheath with a sharp blade or instrument, furnishing a line slit for the access of the electrolyte to the active matter or material without presenting the metal of the grid to the direct contact of the electrolyte, or the porosity required for the envelop or sheath can be obtained chemically by mixing with the solution of tetrabutyrat of cellulose a powdered metal or a soluble salt which by immersion of the plate in the acidbath will cause the acid to eat out the metal or the salt and form holes at places where the particles of metal or salt were located, which holes will permit of the electrolyte to reach the active material and keep the electrolyte from coming in direct contact with the metal of the grid beneath the active material.

This porous protective envelop or sheath is applicable to storage-battery plates or electrodes generally irrespective of the form or dimensions of the plate or electrode, and in use the plate or electrode, as to the metal grid, will be protected against the effects of the electrolyte, and at the same time the active material is open to the admission of the electrolyte thereto. The envelop or sheath formed by dipping the filled plate in a solution of tetrabutyrat of cellulose is elastic in nature and draws tightly over the active matter or material and the grid, pressing the active matter or material firmly against the supporting conductive grid and positively holding the active matter or material in place on the grid, thereby preventing the active matter or material from becoming loose or detaching itself from the grid or metal conductive plate, enabling a comparatively thin supporting and conductive grid or metal plate to be used with the active matter or material applied thereto without the ill effects arising from the loosening and dropping off of the active material, and the firm binding of the active material onto the grid by the draw of the sheath or envelop prevents the electrolyte from attacking the metal of the grid underneath the active material, the active material being held too close and snug for the electrolyte to pass thereunder.

What I claim as new, and desire to secure by Letters Patent, is

1. A protective coating or covering for storage-battery plates or electrodes, consisting of an envelop or sheath formed by dipping the plate or electrode, with the active material thereon, into a solution of tetrabutyrat of cellulose, substantially as described.

2. A protective coating or covering for storage-battery plates or electrodes, consisting of an envelop or sheath formed by dipping the plate or electrode, with the active material thereon, into a solution having tetrabutyrat of cellulose as its base, substantially as described.

ACHILLE MEYGRET.

lVitnesses:

CHAS. H. WHITING, H. R. VVoL'rMANN. 

